1 files changed, 38 insertions, 0 deletions
diff --git a/db/migrate/20180201110056_add_foreign_keys_to_todos.rb b/db/migrate/20180201110056_add_foreign_keys_to_todos.rb
new file mode 100644
index 00000000000..b7c40f8c01a
--- /dev/null
+++ b/db/migrate/20180201110056_add_foreign_keys_to_todos.rb
@@ -0,0 +1,38 @@
+class AddForeignKeysToTodos < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  class Todo < ActiveRecord::Base
+    self.table_name = 'todos'
+    include EachBatch
+  end
+
+  BATCH_SIZE = 1000
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    Todo.where('NOT EXISTS ( SELECT true FROM users WHERE id=todos.user_id )').each_batch(of: BATCH_SIZE) do |batch|
+      batch.delete_all
+    end
+
+    Todo.where('NOT EXISTS ( SELECT true FROM users WHERE id=todos.author_id )').each_batch(of: BATCH_SIZE) do |batch|
+      batch.delete_all
+    end
+
+    Todo.where('note_id IS NOT NULL AND NOT EXISTS ( SELECT true FROM notes WHERE id=todos.note_id )').each_batch(of: BATCH_SIZE) do |batch|
+      batch.delete_all
+    end
+
+    add_concurrent_foreign_key :todos, :users, column: :user_id, on_delete: :cascade
+    add_concurrent_foreign_key :todos, :users, column: :author_id, on_delete: :cascade
+    add_concurrent_foreign_key :todos, :notes, column: :note_id, on_delete: :cascade
+  end
+
+  def down
+    remove_foreign_key :todos, :users
+    remove_foreign_key :todos, column: :author_id
+    remove_foreign_key :todos, :notes
+  end
+end